#include <bits/stdc++.h>
using namespace std;

inline int get_num() {
    int k = 0, f = 1;
    char c = getchar();
    for(; !isdigit(c); c = getchar()) if(c == '-') f = -1;
    for(; isdigit(c); c = getchar()) k = k * 10 + c - '0';
    return k * f;
}

int main() {
    freopen("alice.in", "r", stdin);
    freopen("alice.out", "w", stdout);
    int c = get_num();
    while(c--) {
        double x[3], y[3];
        for(int i = 0; i < 3; i++) {
            x[i] = get_num();
            y[i] = get_num();
        }
        double a = sqrt(abs(x[1] - x[0]) * abs(x[1] - x[0]) + abs(y[1] - y[0]) * abs(y[1] - y[0]));
        double b = sqrt(abs(x[2] - x[0]) * abs(x[2] - x[0]) + abs(y[2] - y[0]) * abs(y[2] - y[0]));
        double c = sqrt(abs(x[1] - x[2]) * abs(x[1] - x[2]) + abs(y[1] - y[2]) * abs(y[1] - y[2]));
        double s = (a + b + c) / 2;
        printf("%.1lf\n",  5.0 * sqrt(s * (s - a) * (s - b) * (s - c)) / 9);
    }
}
